The invention relates generally to electrostatic spray systems, and more particularly, to methods and devices for controlling electrostatic spray guns having memory devices associates therewith that store the spray gun""s operating parameters and identification information.
Electrostatic spray systems apply powder paints and coatings to a variety of products including, for example, appliances, automotive components, metal office furniture/storage shelving, electrical transformers, and recreational equipment. A critical component of such spray systems is a spray gun and a spray gun controller, and more particularly, the power supply for the spray gun and the control of that power supply by the controller. The spray gun and the spray gun controller are responsible for generating a corona-charging effect that is the basis of electrostatic spray systems.
In corona-charging systems, the power supply charges the gun electrode to a high voltage which produces an electric field between the spray gun and a part to be painted. Powder is sprayed through the area of the electric field. Passing through this area, the powder particles are charged and are drawn to the usually grounded part to be painted. In this manner, the part to be painted is coated with powder paint.
In prior art systems, controllers are set up to control a xe2x80x9cstandardizedxe2x80x9d power supply. This means that a set of standard drive voltages and drive currents are used to drive the power supply associated with each spray gun, and, likewise, standard feedback current information from the power supply is used to monitor and control each of the power supplies. In fact, however, there is a great deal of variance between power supplies. Power supplies are built from capacitors and diodes and other components which are potted. There""s often a variation between these components, and in the potting material as well. Consequently, there is often variation in the drive voltage and drive current which is necessary to produce a given electrostatic effect from one spray gun to another spray gun of the same model. Up to now, however, controllers have been incapable of distinguishing between power supplies since no information has been provided which can be used to identify individual performance parameters with each power supply.
In accordance with the present invention, optimization of this powder painting process can be achieved by providing a system and method by which a spray gun controller can identify the type of spray gun it is controlling and monitor and optimize parameters associated with the operation of the particular power supply for each spray gun.
According to one embodiment of the present invention, a method of controlling an electrostatic spray gun power supply is provided. The method includes, for example, the steps of: storing the parameter data associated with a particular spray gun power supply in a memory device associated with the spray gun and using that data to monitor and control the gun""s power supply. The parameter data preferably includes the maximum drive voltage, drive current, and feedback current of the spray gun. The memory device may be, for example, integral with the spray gun or a cable connector that connects to the spray gun. Typically,the power supply is molded into the body of the spray gun. Optimally, a semiconductor chip that carries parameter information for the power supply would be molded into the power supply or the housing for the gun. This information would then be read by the controller though the electric cable that connects the controller to the spray gun.
According to another embodiment of the present invention, a method of determining and storing spray gun power supply information is also provided. The method includes, for example, the steps of: placing a spray gun in a test system to generate parameter information relating to the spray gun power supply, and storing that information in a memory device associated with the spray gun. The memory device may be, for example, integral with the spray gun or a cable connector that connects to the spray gun.
According to yet another embodiment of the present invention, a method of identifying a spray gun type or model is provided. The method includes, for example, the steps of: reading spray gun identification information from an identification device associated with the spray gun and determining the type of spray gun based on the read spray gun identification information. The information to be read can be in the form of analog or digital information. The analog information can be, for example, a voltage, current, or resistance value. The digital information can be, for example, binary. Each value, whether analog or digital, identifies a particular type of spray gun or model.
According to yet another embodiment of the present invention, a system for controlling a spray gun is provided. The system preferably includes one or more spray guns for spraying material onto objects, a data device associated with each spray gun, and a spray gun controller for reading the data device associated with each spray gun and controlling the spray gun based thereon. The data device can be one of several embodiments including, for example, a resistor, a bit pattern as represented by a combination of open or short-circuited connections, or a circuit board having a memory thereon. The data stored in the data device may include, for example, spray gun type identification information and/or operating parameter information for the power supply of the spray gun.
According to yet another embodiment of the present invention, a spray gun assembly is provided. The spray gun assembly includes, for example, a spray dispensing sub-assembly and a data device having information associated with the spray gun assembly. The data device can be one of several embodiments including, for example, a resistor, a bit pattern as represented by a combination of open or short-circuited connections, or a circuit board having a memory thereon. The data stored in the data device includes at least spray gun type identification information and/or operating parameter information for the power supply of the spray gun.
According to yet another embodiment of the present invention, a spray gun cable is provided. The cable includes, for example, a plurality of electrical conductors, arid a connector portion for connecting to a spray gun. The connector portion includes a data device having spray gun data stored therein. The data device can be one of several embodiments including, for example, a resistor, a bit pattern as represented by a combination of open or short-circuited connections, or a circuit board having a memory thereon. The data stored in the data device includes at least spray gun type identification information and/or operating parameter information for the power supply of the spray gun.
It is therefore an advantage of the present invention to provide a system and method for automatically identifying various types of electrostatic spray guns.
It is a further advantage of this invention to provide a system and method for utilizing the operating parameters associated with the individual power supply of each spray gun to more optimally operate an electrostatic spray gun coating system.